Strong and affordable location privacy in VANETs: Identity diffusion using time-slots and swapping

Public acceptance, and thus the economical success of Vehicular Ad Hoc Networks (VANETs), is highly dependent on the quality of deployed privacy mechanisms. Neither users nor operators should be able to track a given individual. One approach to facilitate this is the usage of pseudonym pools, which allow vehicles to autonomously switch between different identities. We extend this scheme with that of a time-slotted pseudonym pool of static size, reducing the storage and computation needs of the envisioned Intelligent Transportation System (ITS) while further improving users' privacy. In addition, we allow the exchange of pseudonyms between nodes, eliminating the mapping between vehicles and pseudonyms even for operators of the VANET. Here, we support the exchange of both the currently used pseudonym and those of future time-slots, further enhancing users' privacy. We evaluate the feasibility of our approach and back up privacy claims by performing a simulative study of the system using the entropy of nodes' anonymity sets as the primary metric.